Compressor

ABSTRACT

A compressor includes a suction chamber, a working chamber, a discharge chamber, a discharge valve and a thermal insulating member. A low-pressure compressible fluid resides in the suction chamber. The low-pressure compressible fluid in the suction chamber is introduced into the working chamber and is compressed to a predetermined pressure. The compressed compressible fluid in the working chamber is discharged into the discharge chamber. The discharge valve is interposed between the working chamber and the discharge chamber. The thermal insulating member is disposed in the discharge chamber. The thermal insulating member has an opening restricting portion for restricting the maximum opening degree of the discharge valve.

BACKGROUND OF THE INVENTION

The present invention relates to a compressor which introduces alow-pressure compressible fluid for compression and discharges acompressed compressible fluid.

A swash plate type compressor is generally known as a compressor for usein a vehicle air conditioning apparatus. A compressor of this type isdisclosed in Japanese Unexamined Patent Publication No. 5-164042. Thecompressor includes a cylinder block which forms therein a cylindricalworking chamber (or compression chamber) in which a piston is receivedfor compressing a compressible fluid such as refrigerant gas. Thecompressor also includes a housing which covers the working chamber ofthe cylinder block and a valve port plate which is interposed betweenthe housing and the cylinder block. The valve port plate has a suctionport through which a low-pressure compressible fluid is introduced froma suction chamber formed in the housing into the working chamber. Thevalve port plate has also a discharge port through which a compressiblefluid compressed by the piston is discharged into a discharge chamberformed in the housing.

The compressor has also a discharge valve plate (or discharge plate)interposed between the valve port plate and the housing and made of ametal. The discharge valve plate has a plurality of discharge valveswhich is integrally formed with the discharge valve plate. When acompressed compressible fluid with high pressure is discharged throughthe discharge port, the discharge valve may be deformed in excess of theelastic limit of the discharge valve plate. Therefore, the compressorhas a retainer which is formed on the side opposite to the dischargeport with respect to the discharge valve for restricting the maximumopening degree of the discharge valve so that the opening degree iswithin the elastic limit of the discharge valve plate.

Meanwhile, the temperature of the compressed compressible fluiddischarged from the working chamber into the discharge chamber isincreased by the compression in the working chamber. Part of the heat ofthe compressed compressible fluid is transferred to the compressiblefluid in the suction chamber thereby causing the compressible fluidbefore compression to be expanded. Consequently, the amount of gassubstantially introduced into the working chamber is reduced and,therefore, the compression efficiency of the compressor is reduced. Toprevent such heat transfer, this compressor has a partition which isformed in the housing so as to define the discharge chamber and thesuction chamber, and an annular groove is formed in the partition whichserves as a thermal insulating member for preventing the heat transferof the compressible fluid in the discharge chamber to the suctionchamber.

A compressor which prevents the heat transfer of the compressedcompressible fluid in the discharge chamber to the suction chamber in asimilar manner is disclosed in Japanese Unexamined Patent PublicationNo. 2004-11531. Further, another compressor which uses rubber or resinserving as thermal insulating means is disclosed in Japanese UnexaminedPatent Publication No. 2002-235667.

However, these prior art compressors merely adds thermal insulatingmeans for preventing the heat transfer of the compressible fluid in thedischarge chamber to the suction chamber thereby achieving a thermalinsulating effect. To merely provide additional thermal insulating meanscauses problems such as increased number of parts, enlargement of thecompressor, and reduced design freedom due to increased installationspace.

SUMMARY OF THE INVENTION

The present invention is directed to a compressor having a thermalinsulating member which prevents the heat transfer of compressible fluidin a discharge chamber to a suction chamber while serving as a retainer,thereby enabling reduction of the number of parts, simplification of thecompressor, or reduction of the size of the compressor while maintainingthe compression efficiency of the compressor.

The present invention provides the following feature. A compressorincludes a suction chamber, a working chamber, a discharge chamber, adischarge valve and a thermal insulating member. A low-pressurecompressible fluid resides in the suction chamber. The low-pressurecompressible fluid in the suction chamber is introduced into the workingchamber and is compressed to a predetermined pressure. The compressedcompressible fluid in the working chamber is discharged into thedischarge chamber. The discharge valve is interposed between the workingchamber and the discharge chamber. The thermal insulating member isdisposed in the discharge chamber. The thermal insulating member has anopening restricting portion for restricting the maximum opening degreeof the discharge valve.

Other aspects and advantages of the invention will become apparent fromthe following description, taken in conjunction with the accompanyingdrawings, illustrating by way of example the principles of theinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

The features of the present invention that are believed to be novel areset forth with particularity in the appended claims. The invention,together with objects and advantages thereof, may best be understood byreference to the following description of the presently preferredembodiments, together with the accompanying drawing, in which:

FIG. 1 is a longitudinal sectional view showing a compressor accordingto a first preferred embodiment of the present invention;

FIG. 2 is an explanation drawing explaining a thermal insulating memberof the compressor according to the first preferred embodiment of thepresent invention;

FIG. 3 is a longitudinal sectional view showing a compressor accordingto a second preferred embodiment of the present invention;

FIG. 4 is an explanation drawing explaining a thermal insulating memberof the compressor according to the second preferred embodiment of thepresent invention;

FIG. 5 is a partially enlarged longitudinal sectional view showing acompressor according to a third preferred embodiment of the presentinvention; and

FIG. 6 is a partially enlarged longitudinal sectional view showing acompressor according to a fourth preferred embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following will describe a compressor according to a first preferredembodiment of the present invention with reference to FIGS. 1 and 2. Itis noted that the left side of the compressor in FIG. 1 is the frontside and the opposite right side thereof is the rear side. Thecompressor according to the first preferred embodiment is a variabledisplacement type compressor which uses carbon dioxide as a compressiblefluid.

FIG. 1 shows a compressor 10 of the first embodiment. Referring to FIG.1, the compressor 10 includes a compressor housing 11 which forms theouter shell of the compressor 10. The compressor housing 11 includes acylinder block 12 in which a plurality of cylinder bores 12 a is formed,a front housing 13 which is joined to the front end of the cylinderblock 12 and a rear housing 14 which is joined to the rear end of thecylinder block 12. In the first preferred embodiment, the front housing13, the cylinder block 12 and the rear housing 14 of the compressorhousing 11 are made of aluminum-based metal to reduce the compressorweight. A plurality of through bolts 16 (only one shown in FIG. 1)extends through the front housing 13, the cylinder block 12 and the rearhousing 14 and tightens those components together in the axial directionthereof, thereby integrally fixing those components to form thecompressor housing 11.

The front housing 13 and the cylinder block 12 cooperate to define acrank chamber 17 whose rear side is closed by the cylinder block 12. Arotatable drive shaft 18 extends through the crank chamber 17 at thecenter thereof. The drive shaft 18 is supported at the front portionthereof by a radial bearing 19 which is disposed in the front housing 13and at the rear portion thereof by a radial bearing 20 which is disposedin the cylinder block 12. A shaft seal mechanism 33 is provided on thefront side of the radial bearing 19 in sliding contact with the outerperipheral surface of the drive shaft 18. The shaft seal mechanism 33includes a lip seal member and a holder which holds the lip seal member,thereby preventing compressible fluid in the crank chamber 17 fromleaking through a gap between the front housing 13 and the drive shaft18.

A lug plate 21 is fixed to the drive shaft 18 in the crank chamber 17for rotation therewith. A swash plate 23 which forms a displacementchanging mechanism 22 is supported by the drive shaft 18 at the rearside of the lug plate 21 so as to slide along and incline with respectto the axis of the drive shaft 18. A hinge mechanism 24 is interposedbetween the swash plate 23 and the lug plate 21, and the swash plate 23is connected to the lug plate 21 and the drive shaft 18 through thehinge mechanism 24 for synchronous rotation therewith and inclinationwith respect thereto.

A coil spring 25 is provided around the drive shaft 18 between the lugplate 21 and the swash plate 23, and a tubular body 26 is slidablyfitted on the drive shaft 18 and urged rearward by the coil spring 25.Thus, the swash plate 23 is constantly pushed rearward by the coilspring 25 through the tubular body 26 in such a way the swash plate 23is urged in the direction which reduces inclination angle of the swashplate 23. It is noted that the inclination angle of the swash plate 23is an angle between a plane perpendicular to the axial direction of thedrive shaft 18 and a plane of the swash plate 23. A stopper 23 aprotrudes from the front side of the swash plate 23, and as shown inFIG. 1, the contact of the stopper 23 a with the lug plate 21 restrictsthe position of the maximum inclination of the swash plate 23. Aretaining ring 27 is installed on the drive shaft 18 on the rear side ofthe swash plate 23, and a coil spring 28 is provided around the driveshaft 18 on the front side of the retaining ring 27. The contact of theswash plate 23 with the coil spring 28 restricts the position of theminimum inclination of the swash plate 23. A single-headed piston 29 isreceived in each cylinder bore 12 a of the cylinder block 12 forreciprocation therein, and a neck portion of each piston 29 engages withthe periphery of the swash plate 23 through a corresponding pair ofshoes 30.

A displacement control valve 32 is provided in the rear housing 14 whichis operable to adjust the stroke of the piston 29 or the displacement ofthe compressor 10 by changing the angle of inclination of the swashplate 23.

The rear housing 14, a valve port plate 35 and a suction valve plate 34which are interposed between the rear housing 14 and the cylinder block12, a discharge valve plate 36 and a thermal insulating member 37 willnow be described. The rear housing 14 which is joined to the rear end ofthe cylinder block 12 has a suction chamber 14 a formed in the rearhousing 14 and a discharge chamber 14 b in which the thermal insulatingmember 37, which will be described in detail later, is provided. Thevalve port plate 35 forms a working chamber 31 in each cylinder bore 12a with the corresponding piston 29. The valve port plate 35 has asuction port 35 a which is in communication with the suction chamber 14a in the rear housing 14 and a discharge port 35 b which is incommunication with the discharge chamber 14 b in the rear housing 14.The discharge port 35 b serves as a valve port. The suction valve plate34 is a plate which has suction valves (not shown) interposed betweenthe working chambers 31 and the suction ports 35 a, while the dischargevalve plate 36 is a plate which has reed type discharge valves 36 ainterposed between the discharge ports 35 b and the discharge chambers14 b. The thermal insulating member 37 is disposed in the dischargechamber 14 b of the rear housing 14 and has a discharge space 37 aformed in the thermal insulating member 37. The thermal insulatingmember 37 is provided to prevent the heat transfer of the compressiblefluid in the discharge space 37 a to the suction chamber 14 a. Inaddition, the thermal insulating member 37 has an opening restrictingportion 37 b for restricting the maximum opening degree of the dischargevalve 36 a.

To describe more in detail with reference to FIG. 1, while the front endof the rear housing 14 and the rear end of the cylinder block 12 arejoined to each other, the valve plates 34, 36 are disposed between therear housing 14 and the cylinder block 12 with the valve port plate 35interposed therebetween. That is, the suction valve plate 34 is locatedon the front side of the valve port plate 35 and the discharge valveplate 36 is located on the opposite rear side thereof. The thermalinsulating member 37 is disposed on the side of the rear housing 14 withrespect to the discharge valve plate 36. In the first preferredembodiment, the suction valve plate 34, the valve port plate 35, thedischarge valve plate 36 and the thermal insulating member 37 arearranged in this order from the front side, and a bolt 38 extendsthrough the valve plates 34, 36, the valve port plate 35 and the thermalinsulating member 37. A nut 40 is screwed on the bolt 38 for fasteningthe valve plates 34, 36, the valve port plate 35 and the thermalinsulating member 37 by way of two disc springs 39. Thus, the thermalinsulting member 37 is constantly urged against the discharge valveplate 36 by the resilient force of the disc springs 39. Although in thefirst preferred embodiment the disc springs 39 are used as the urgingmember for providing urging force to the thermal insulating member 37,members other than the disc springs 39 may be used, such as resilientmember made of rubber-based material or resilient sealing member.

The suction chamber 14 a is formed in radially outer region of the rearhousing 14 in communication with the cylinder bore 12 a via the suctionport 35 a formed through the valve port plate 35. On the other hand, thedischarge chamber 14 b, in which the thermal insulating member 37 isprovided, is formed in radially inner region of the rear housing 14. Thedischarge chamber 14 b and the suction chamber 14 a are separatedsealingly from each other by a partition 14 c. The discharge space 37 ais formed in the thermal insulating member 37 so as to face thedischarge valve plate 36.

The discharge valve plate 36 is made of a thin metal sheet which has thereed type discharge valve 36 a for opening and closing the dischargeport 35 b formed through the valve port plate 35. As shown in FIG. 2,the discharge valve 36 a corresponds to each of the discharge ports 35 bwhich is correspond to the cylinder bore 12 a, and a proximal end 361 ofthe discharge valve 36 a which is located on the center of the rearhousing 14 is fixed between the valve port plate 35 and the thermalinsulating member 37 by being pressed by the thermal insulating member37 which is urged frontward by the disc springs 39. The discharge valve36 a is flexible as the chain line shown in FIG. 2, and the maximumopening degree of the discharge valve 36 a is restricted by contactthereof with the opening restricting portion 37 b of the thermalinsulating member 37.

The thermal insulating member 37 of the first preferred embodiment willnow be described in detail. FIG. 2 shows a front view of the thermalinsulating member 37 as seen from the discharge valve plate 36 (drawingon the left). FIG. 2 also shows a longitudinal-sectional view of thethermal insulating member 37 drawing on the right). The valve port plate35 and the discharge valve plate 36 are illustrated by solid and chainlines. The thermal insulating member 37 has a substantially disk-likeshape. The thermal insulating member 37 also has a plurality of recesses37 c arranged circumferentially in facing to the discharge valve plate36 and each having substantially a sector shape. The recesses 37 c areformed in the thermal insulating member 37 adjacent to the periphery ofthe thermal insulating member 37. The opening restricting portion 37 bis formed between any two adjacent recesses 37 c and a communicationgroove 37 d is formed adjacent to the outer periphery of the recesses 37c for communication between the recesses 37 c. In the first preferredembodiment, these recesses 37 c and the communication grooves 37 d formthe discharge space 37 a.

The opening restricting portion 37 b has a curved surface as shown inthe cross section of FIGS. 1 and 2, so that no harmful force is appliedto the discharge valve 36 a when the discharge valve 36 a is fullyopened in contact with the opening restricting portion 37 b. As shown inFIG. 2, one of the recesses 37 c of the thermal insulating member 37 hasan outlet 37 e which is in communication with a discharge piping (brokenline shown in FIG. 1) connected to an external refrigerant circuit. Theoutlet 37 e is formed on the one recess 37 c. The thermal insulatingmember 37 prevents the heat transfer of the compressible fluid in thedischarge space 37 a to the rear housing 14 including the suctionchamber 14 a, because the thermal insulating member 37 is made of resinmaterial which has a smaller heat transfer coefficient than the rearhousing 14 which is made of aluminum-based metal in the presentembodiment. In the first preferred embodiment, PPS (polyphenylenesulfide) resin is used as the resin material.

In the first preferred embodiment, a contacted portion 371 formed in thethermal insulating member 37 is contacted with the proximal end 361 ofthe discharge valve 36 a, that is, the contacted portion 371 is pressedagainst the proximal end 361. This contacted portion 371 is defined by acircular region of the thermal insulating member 37, as shown bylatticed hatching in FIG. 2, which ranges from the center thereof to theopening restricting portion 37 b. The discharge valve plate 36 is keptin tight contact with the thermal insulating member 37 at the contactedportion 371 thereof, so that irregular movement of the discharge valve36 a relative to the valve port plate 35 is prevented when the dischargevalve 36 a is opened and closed.

The operation of the compressor 10 of the first preferred embodimentwill now be described. As the drive shaft 18 is rotated and the swashplate 23 is driven to rotate accordingly, each piston 29 is reciprocatedthrough the shoes 30. When the piston 29 moves from its top dead centerto its bottom dead center, the compressible fluid in the suction chamber14 a is drawn into the working chamber 31 in the cylinder bore 12 athrough the suction valve. Then, when the piston 29 moves from thebottom dead center to the top dead center, the compressible fluid in theworking chamber 31 is compressed to a predetermined pressure, and thendischarged into the discharge space 37 a through the discharge valve 36a. Although the compressible fluid in the discharge space 37 a is thenhigh in temperature and pressure, the heat transfer of the compressiblefluid in the discharge space 37 a to the suction chamber 14 a isprevented by the thermal insulating member 37, thereby preventingtemperature rise of the low-pressure compressible fluid in the suctionchamber 14 a. During the operation of the compressor 10, the dischargevalve 36 a is not opened or bent in excess of its elastic limit by thecontact with the opening restricting portion 37 b of the thermalinsulating member 37. The compressible fluid discharged into thedischarge space 37 a of the thermal insulating member 37 is dischargedfrom the outlet 37 e to the discharge piping through the communicationgroove 37 d, which is in communication with the adjacent recesses 37 c.

The compressor 10 of the first preferred embodiment has the followingadvantageous effects.

-   -   (1) The thermal insulating member 37 not only prevents the heat        transfer of the compressible fluid in the discharge space 37 a        to the rear housing 14 including the suction chamber 14 a but        also serves as a retainer. Therefore, the number of parts of the        compressor 10 is reduced as compared to that of a prior art        compressor. In addition, the space for installation is reduced        as compared to the case in which the retainer and the thermal        insulating member are separately installed, thus enabling the        compressor 10 to be simplified and reduce its size. Further, the        freedom of designing the interior of the rear housing 14 is        enhanced. Further, the reduced number of parts enables reduction        of manufacturing cost and simplification of assembling        operation.    -   (2) Because the opening restricting portion 37 b of the thermal        insulating member 37 has an arched surface in cross section, the        discharge valve 36 a of the discharge valve plate 36 is opened        along the arched surface in its maximum opening degree. Thus,        the discharge valve 36 a is not opened in excess of its elastic        limit and the valve 36 a is not susceptible to excessive        deformation or breakage.    -   (3) In the above-described embodiment wherein the thermal        insulating member 37 is urged against the discharge valve plate        36 by the disc springs 39 serving as the urging member, the        discharge valve plate 36 is firmly pressed against the thermal        insulating member 37 and the valve port plate 35. Therefore, the        pressed contact of the discharge valve plate 36 with both of the        valve port plate 35 and the thermal insulating member 37 is        maintained when the discharge valve 36 a is fully opened,        thereby stabilizing the opening and closing operation of the        discharge valve 36 a.    -   (4) The thermal insulating member 37 is pressed against the        discharge valve plate 36 thereby maintaining fluid tightness of        the discharge space 37 a. Also, since the thermal insulating        member 37 is pressed against the discharge valve plate 36, the        surface of the thermal insulating member 37 with which the        discharge valve plate 36 is contacted does not require highly        accurate machining, thereby facilitating the machining of the        thermal insulating member 37. This is particularly effective        when the thermal insulating member 37 is made of resin material.    -   (5) Using a resin as the material for the thermal insulating        member 37, it is easier to set the heat transfer coefficient of        the thermal insulating member 37 lower than that of the housing        11 made of metal and forming the outer shell of the compressor        and to make the opening restricting portion 37 b as compared        with the conventional practice according to which the thermal        insulating member and the opening restricting portion are formed        separately. Thus, the manufacture of the compressor 10 is        simplified.    -   (6) In a case where carbon dioxide is employed as the        compressible fluid which is used under a relatively high        pressure as compared to another compressible fluid, the carbon        dioxide generates a greater amount of heat in the discharge        space 37 a. As the temperature of the carbon dioxide in the        discharge space 37 a rises, the prevention effect of the heat        transfer of the compressible fluid to the suction chamber 14 a        by the thermal insulating member 37 becomes more remarkable.    -   (7) The prevention effect of the thermal insulating member 37 is        improved by increasing the thickness thereof. If the thermal        insulating member 37 is formed with a sufficiently large        thickness, the prevention effect of the heat transfer of the        compressible fluid in the discharge space 37 a to the suction        chamber 14 a is further improved, thereby enhancing the        compression efficiency of the compressor 10.    -   (8) As the number of cylinder bores 12 a in the cylinder block        12 of the compressor 10 is increased, the diameter of the        cylinder bores and the size of the discharge valves 36 a are        reduced. However, in the above-described embodiment of the        invention wherein the thermal insulating member 37 is formed        integrally with the opening restricting portion 37 b, the        maximum opening degree of the discharge valves 36 a can be        restricted easily in a compressor having an increased number of        cylinder bores.

A compressor 50 according to a second preferred embodiment of thepresent invention will now be described with reference to FIGS. 3 and 4.As shown in FIG. 3, the compressor 50 according to the second preferredembodiment is different from the compressor 10 according to the firstpreferred embodiment in that a discharge chamber 54 b is formed inradially outer region of a rear housing 54 and that a suction chamber 54a is formed in radially inner region thereof. For convenience ofexplanation, the drawings for the second embodiment use like referencenumerals or symbols to denote like parts or elements of the firstembodiment. Explanation of those parts which are common to the first andsecond embodiments is omitted, and the explanation of the firstembodiment is incorporated in the second preferred embodiment.Therefore, the following description will deal with mainly thedifferences from the first preferred embodiment.

As shown in FIGS. 3 and 4, the cylinder block 12 is joined at the rearend thereof to the front end of the rear housing 54 with a suction valveplate 53, a discharge valve plate 56 and a valve port plate 55interposed therebetween. The suction valve plate 53 is located on thefront side of the valve port plate 55 and the discharge valve plate 56is located on the opposite rear side thereof. In the radially outerregion of the rear housing 54, the discharge chamber 54 b is annularlyformed. An annular thermal insulating member 57 which forms a dischargespace 57 a is disposed in the discharge chamber 54 b. In the radiallyinner region of the rear housing 54, a suction chamber 54 a is formed.The valve port plate 55 has a suction port 55 a corresponding to thesuction chamber 54 a and a discharge port 55 b that serves as a valveport through the valve port plate 55. The discharge port 55 bcorresponds to the discharge space 57 a formed by the thermal insulatingmember 57. The suction valve plate 53 which forms a suction valve isinterposed between the suction port 55 a of the valve port plate 55 andthe working chamber 31. The discharge valve plate 56 formed annularlyand having a discharge valve 56 a is interposed between the dischargeport 55 b of the valve port plate 55 and the discharge space 57 a. Thedischarge valve 56 a of the discharge valve plate 56 extends from anannular proximal end 561 of the discharge valve plate 56 toward thecenter of the discharge valve plate 56. The discharge valve 56 a isformed at a position corresponding to the discharge port 55 b.

The thermal insulating member 57 will now be described in detail. Asshown in FIG. 4, the thermal insulating member 57 of the secondpreferred embodiment is made in the form of a gear and has a throughhole 57 e formed in the central region of the thermal insulating member57. FIG. 4 shows a front view of the thermal insulating member 57 whichis seen from the discharge valve plate 56 (drawing on the left). FIG. 4also shows a longitudinal-sectional view of the thermal insulatingmember 57 (drawing on the right). The valve port plate 55 and thedischarge valve plate 56 are illustrated by solid line and chain line. Acommunication groove 57 c is formed in the outer peripheral portion ofthe thermal insulating member 57 along the outline of the gear-likeshape thereof. In the present embodiment, the communication groove 57 csubstantially corresponds to the discharge space 57 a. An openingrestricting portion 57 b of a bell-like shape is formed so as to besurrounded on three sides thereof by the communication groove 57 c. Thedischarge valve 56 a is formed so as to face the opening restrictingportion 57 b. Because the opening restricting portion 57 b has an archedsurface in cross section, the discharge valve 56 a is opened along thearched surface in its maximum opening position. Thus, the dischargevalve 56 a is not opened in excess of its elastic limit and thedischarge valve 56 a is not susceptible to excess deformation or break.

In FIGS. 3 and 4, the rear housing 54 also serves as an urging member tourge the thermal insulating member 57 toward the discharge valve plate56 through the bolts 16, thereby pressing the thermal insulating member57 against the discharge valve plate 56. Thus, the proximal end 561 ofthe discharge valve 56 a is held securely by the thermal insulatingmember 57 and the valve port plate 55. Therefore, the discharge valveplate 56 makes steady opening and closing motion without irregularmotion when the discharge valve 56 a is in its maximum opening degree.One of the communication grooves 57 c of the thermal insulating member57 has an outlet 57 d which is in communication with a discharge piping(not shown). The outlet 57 d is formed on the one communication groove57 c. The compressible fluid in the communication groove 57 c thatserves as the discharge space 57 a is discharged to the discharge pipingthrough the outlet 57 d. As in the first preferred embodiment, a portionof the thermal insulating member 57 which is contacted with the proximalend 561 of the discharge valve 56 a, that is, a contacted portion 571 isformed in the thermal insulating member 57. In the present preferredembodiment, the contacted portion 571 is shown by latticed regions inFIG. 4.

According to the compressor 50 of the present preferred embodiment, whenthe piston 29 moves from its bottom dead center to its top dead center,the compressible fluid in the working chamber 31 is compressed to apredetermined pressure and then discharged into the discharge space 57 athrough the discharge valve 56 a. Although the compressible fluid in thedischarge space 57 a is then high in temperature and pressure, the heattransfer of the compressible fluid to the rear housing 54 including thesuction chamber 54 a is prevented by the thermal insulating member 57,thereby preventing temperature rise of the low-pressure compressiblefluid in the suction chamber 54 a. During the operation of thecompressor 50, the discharge valve 56 a is not opened or bent in excessof its elastic limit by the contact with the opening restricting portion57 b of the thermal insulating member 57. The compressible fluiddischarged into the discharge space 57 a of the thermal insulatingmember 57 is discharged from the outlet 57 d to the discharge piping.

As is apparent to those skilled in the art, though the compressor 50 ofthe second embodiment differs from the compressor 10 of the firstembodiment in that the suction chamber 54 a is formed in radially innerregion while the discharge space 57 a is formed in radially outer regionof the rear housing 54, the compressor 50 having the thermal insulatingmember 57 offers substantially the same effects as the compressor 10.

A compressor 60 according to a third preferred embodiment of the presentinvention will now be described with reference to FIG. 5. Forconvenience of explanation, the drawing for the third embodiment useslike reference numerals or symbols to denote like parts or elements ofthe first embodiment. Explanation of those parts which are common to thefirst and third embodiments is omitted, and the explanation of the firstembodiment is incorporated in the third preferred embodiment. Therefore,the following description will deal with mainly the differences from thefirst preferred embodiment. Accordingly, FIG. 5 shows only those partsof the compressor 60 which are relevant to the third embodiment. Thecompressor 60 according to the third preferred embodiment has a suctionchamber 64 a which is formed in the radially outer region of a rearhousing 64 and a discharge chamber 64 b having a thermal insulatingmember 67 disposed therein is formed in the radially inner region of therear housing 64. The suction chamber 64 a and the discharge chamber 64 bare separated from each other by a partition 64 c. The cylinder block 12is joined at the rear end thereof to the front end of the rear housing64. Between the cylinder block 12 and the rear housing 64, a suctionvalve plate 63 which forms a suction valve, a valve port plate 65 whichforms a discharge port 65 b serving as a valve port and a dischargevalve plate 66 which forms a discharge valve 66 a are provided. Thesuction valve plate 63 is located on the front side of the valve portplate 65 and the discharge valve plate 66 is located on the rear sidethereof. In the present preferred embodiment, a bolt 68 extends throughthe center of the valve port plate 65 and the valve plates 63, 66, and anut 69 is screwed on the bolt 68 thereby fastening the valve plates 63,66 to the valve port plate 65.

Meanwhile, the thermal insulating member 67, which is disposed in thedischarge chamber 64 b of the rear housing 64, has a discharge space 67a, an opening restricting portion 67 b, a recess 67 c, a communicationgroove 67 d and an outlet 67 e, as in the case of the first embodiment.In the present preferred embodiment, a thermal insulating groove 67 f isfurther formed in the thermal insulating member 67 on the radially outerside of the communication groove 67 d. The thermal insulating groove 67f serves an air space in the thermal insulating member 67 for thermalinsulation, and the thermal insulating effect of the air space furtherenhances the prevention effect of the heat transfer of the compressiblefluid in the discharge space 67 a to the rear housing 64 including thesuction chamber 64 a. That is, it can be said that the air space whichserves as thermal insulating means having a heat transfer coefficientthat is smaller than that of the thermal insulating member 67 isprovided in the thermal insulating member 67. Thus, while the presentpreferred embodiment employs the thermal insulating groove 67 f as theair space, a material whose heat transfer coefficient is smaller thanthat of the thermal insulating member 67 is suitably selected.

In the present preferred embodiment wherein the rear housing 64 isfastened to the cylinder block 12 by axial force of the through bolts 16and presses the thermal insulating member 67 against the valve portplate 65, the through bolts 16 substantially serves as the urgingmember. The thermal insulating member 67 has a recess 67 g which isopened on the front side of thermal insulating member 67. The recess 67g is formed in the central region of the thermal insulating member 67,and accommodates therein the bolt 68 and the nut 69. In the presentembodiment, the air space serving as the thermal insulating means whoseheat transfer coefficient is smaller than that of the thermal insulatingmember 67 is provided in the thermal insulating member 67, therebyfurther enhancing the prevention effect of the heat transfer of thecompressible fluid in the discharge space 67 a to the suction chamber 64a.

A compressor 70 according to a fourth preferred embodiment of thepresent invention will now be described with reference to FIG. 6. Forconvenience of explanation, the drawing for the fourth embodiment useslike reference numerals or symbols to denote like parts or elements ofthe first embodiment. Explanation of those parts which are common to thefirst and fourth embodiments is omitted, and the explanation of thefirst embodiment is incorporated in the fourth preferred embodiment.Therefore, the following description will deal with mainly thedifferences from the first preferred embodiment. Accordingly, FIG. 6shows only those parts of the compressor 70 which are relevant to thefourth embodiment. The compressor 70 according to the fourth preferredembodiment has a suction chamber 74 a which is formed in the radiallyouter region of a rear housing 74 and a discharge chamber 74 baccommodating a thermal insulating member 77 disposed therein is formedin the radially inner region of the rear housing 74. The suction chamber74 a and the discharge chamber 74 b are separated from each other by apartition 74 c. The cylinder block 12 is joined at the rear end thereofto the front end of the rear housing 74. A suction valve plate 73 whichforms a suction valve, a valve port plate 75 which forms a dischargeport 75 b serving as a valve port, a discharge valve plate 76 whichforms a discharge valve 76 a and a plate 78 for pressing against thedischarge valve plate 76 are provided in this order between the cylinderblock 12 and the rear housing 74.

In the present preferred embodiment, a bolt 79 extends through thecenter of the valve port plate 75, the valve plates 73, 76 and the plate78. A nut 80 is screwed on the bolt 79 thereby fastening the dischargevalve plate 76 to the valve port plate 75. A disc spring 81, throughwhich the bolt 79 extends, is interposed between the plate 78 and thenut 80. The disc spring 81 urges the plate 78 against the dischargevalve plate 76, and serves as the urging means.

Meanwhile, the thermal insulating member 77, which is disposed in thedischarge chamber 74 b of the rear housing 74, has a discharge space 77a, an opening restricting portion 77 b, a recess 77 c, a communicationgroove 77 d and an outlet 77 e, as in the case of the first embodiment.While the thermal insulating member 77 according to the presentpreferred embodiment is pressed against the plate 78, the thermalinsulating member 77 does not directly press against a proximal end 761of the discharge valve 76 a of the discharge valve plate 76. That is,the proximal end 761 of the discharge valve 76 a is mainly pressed bythe plate 78 which receives elastic force of the disc spring 81, and apart of the thermal insulating member 77 is merely contacted with theplate 78. Therefore, the contact between the thermal insulating member77 and the plate 78 may be in such condition that fluid tightness of thedischarge space 77 a is accomplished by providing an adhesive or sealingmember between the thermal insulating member 77 and the plate 78. Thus,the contacted portions 371, 571 which have been explained with referenceto the first and second preferred embodiments do not exist in thethermal insulating member 77 of the fourth preferred embodiment.

In the present preferred embodiment, the opening restricting portion 77b of the thermal insulating member 77 has an arched surface, with whichpart of the discharge valve 36 a is contacted, in cross section.Although the area of the opening restricting portion 77 b with which thedischarge valve 76 a is contacted is smaller than that of the openingrestricting portion 37 b of the first preferred embodiment due to thethickness of the plate 78 interposed between the discharge valve plate76 and the thermal insulating member 77, the opening restricting portion77 b of the thermal insulating member 77 performs the function ofrestricting the maximum opening degree of the discharge valve 76 asubstantially in the same manner as the opening restricting portion 37b. According to the compressor 70 of the present preferred embodiment,while the thermal insulating member 77 prevents the heat transfer of thecompressible fluid in the discharge space 77 a to the rear housing 74including the suction chamber 74 a, the thermal insulating member 77restricts the maximum opening degree of the discharge valve 76 a. Inaddition, since the thermal insulating member 77 does not need to bedirectly pressed against the discharge valve plate 76, the degree offreedom of selecting material of the thermal insulating member 77, forexample, its strength is improved.

While the foregoing descriptions for the first through fourthembodiments has dealt with the swash plate type compressor provided withpistons, the present invention is also applicable to a scroll typecompressor. Although not shown, the scroll type compressor generallyincludes a working chamber which is formed by a fixed scroll and amovable scroll, a suction chamber from which a low-pressure fluid isintroduced into the working chamber, a discharge chamber into which ahigh-pressure fluid compressed in the working chamber is discharged, adischarge valve interposed between the working chamber and the dischargechamber and a retainer which restricts the maximum opening degree of thedischarge valve. By providing a thermal insulating member in which adischarge space and an opening restricting portion for restricting theopening degree of the discharge valve are formed in the dischargechamber of the scroll type compressor, the thermal insulating member canperform the function of preventing the heat transfer from the dischargespace to a housing including the suction chamber and also retaining thedischarge valve opening.

The present invention is not limited to the above-mentioned firstthrough fourth embodiments, but may be modified within the scope of theappended claims, as exemplified below.

While the first through fourth embodiments have been described by way ofan example of variable displacement swash plate type compressor, thepresent invention is applicable to a fixed displacement swash plate typecompressor. At least if the compressor is constructed such that itssuction chamber and discharge chamber are located relatively adjacent toeach other and that a compressible fluid is discharged into thedischarge chamber through a discharge valve, the present invention isapplicable to the fixed displacement swash plate type compressor. Thus,types of compressor to which the present invention is applicable are notlimited.

While the thermal insulating member according to the first throughfourth embodiments is made of a resin material, the thermal insulatingmember may be made of any material whose heat transfer coefficient issmaller than that of a housing made of a metal such as aluminum-based orferrous metal. Any other metals or inorganic materials whose heattransfer coefficient is small may be used.

In each of the first through fourth embodiments, because the thermalinsulating member which serves also as a retainer has a discharge spacetherein, the discharge space prevents the heat transfer of thecompressible fluid in the discharge chamber to the suction chamber,thereby improving the performance of the compressor. However, thesuction chamber may be formed by another thermal insulating member. Inthis case, the heat transfer of the compressible fluid in the dischargechamber to the suction chamber is further prevented by the thermalinsulating member of the suction chamber side and the thermal insulatingmember forming the discharge space, thereby improving the compressionefficiency of the compressor. Thus, the performance of the compressor isfurther enhanced.

In each of the first through fourth embodiments, carbon dioxide which iscompressed to a high pressure is employed as the compressible fluid. Inthe present invention, however, chlorofluorocarbon or Freon gas which iscompressed to a pressure that is lower than that of carbon dioxide maybe employed as the compressible fluid. Thus, kinds of compressible fluidto which the present invention is applicable are not limited.

Therefore, the present examples and embodiments are to be considered asillustrative and not restrictive and the invention is not to be limitedto the details given herein but may be modified.

1. A compressor comprising: a suction chamber in which a low-pressurecompressible fluid resides; a working chamber into which thelow-pressure compressible fluid in the suction chamber is introduced andin which the compressible fluid is compressed to a predeterminedpressure; a discharge chamber into which the compressed compressiblefluid in the working chamber is discharged; a discharge valve interposedbetween the working chamber and the discharge chamber; and a thermalinsulating member disposed in the discharge chamber, wherein the thermalinsulating member has an opening restricting portion for restricting themaximum opening degree of the discharge valve.
 2. The compressoraccording to claim 1, further comprising an urging member for pressingthe thermal insulating member against the discharge valve.
 3. Thecompressor according to claim 1, wherein heat transfer coefficient ofthe thermal insulating member is smaller than that of a housing whichforms an outer shell of the compressor.
 4. The compressor according toclaim 2, wherein the urging member is a spring.
 5. The compressoraccording to claim 2, wherein the urging member is a housing which formsan outer shell of the compressor.
 6. The compressor according to claim1, further comprising a plate for pressing the discharge valve to avalve port plate.
 7. The compressor according to claim 1, wherein thethermal insulating member has a contacted portion which is contactedwith a proximal end of the discharge valve.
 8. The compressor accordingto claim 1, wherein the thermal insulating member has a substantiallydisk-like shape.
 9. The compressor according to claim 1, wherein thethermal insulating member has an annular shape.
 10. The compressoraccording to claim 9, wherein the thermal insulating member has agear-like shape.
 11. The compressor according to claim 1, wherein thethermal insulating member is made of a resin material.
 12. Thecompressor according to claim 1, wherein the opening restricting portionhas an arched surface in cross section.
 13. The compressor according toclaim 1, wherein the compressible fluid is a carbon dioxide.